The Preparation Of Modified Silicone Resins By Sol-Gel Process And Their Application In LED Packaging

Owing to the merits of high luminous efficiency,environmental protection and long service life,light emitting diodes(LEDs)are widely used in many fields such as communication,electronic display,daily lighting etc..And packaging materials are a key component in the practical application of LEDs.At present,the hot materials for LED packaging on the market are epoxy resin and silicone resin.Epoxy resin has the advantages of good mechanical properties,strong cohesive force and low cost,but has the disadvantages of poor resistance to high temperature and ultraviolet aging and large internal stress.And silicone resin has excellent resistance to high temperature and ultraviolet aging as well as moisture resistance,high light transmittance and good electrical insulation.However,silicone resin has poor adhesion to LED substrate,which badly affects its wide application.The combination of epoxy resin and silicone resin can not only improve the performance to resist to high temperature and ultraviolet and to reduce the internal stress of epoxy resin,but also improve the adhesion of silicone resin.Thus,epoxy modified silicone resin has become a research hotspot.In this paper,two kinds of epoxy modified silicone resins were synthesized and then silicone materials with high performance were prepared by different curing ways.Besides,the opening-ring and gel mechanism of epoxy group was explored.The main work as followed.(1)Three types of epoxy modified methyl phenyl silicone resins with different content of epoxy groups were synthesized by an approach of combination of hydrolytic sol-gel and non-hydrolytic sol-gel process.Firstly,using phenyltrimethoxysilane,methylphenyldimethoxysilane as raw materials and anion exchange resin as catalyst,methylphenyl silicone resin with terminal hydroxyl groups(HMPS)was synthesized by means of hydrolytic sol-gel process.And then methylphenyl silicon resin with terminal hydroxyl groups(HMPS)was subjected to non-hydrolytic sol-gel reaction with 3-glycidoxypropylmethyldimethoxysilane.Eventually,epoxy modified methyl phenyl silicone resins with different content of epoxy groups(EMPS)was prepared.And the synthesis process of HMPS and EMPS was optimized and the performance of them also was characterized.Under the optimal synthesis conditions,the molecular weight of HMPS was 685,the molecular weight distribution index was 1.391,the viscosity was 793 mpa.s and the refractive index was 1.544.And the molecular weight of EMPS was 4137,the molecular weight distribution index was 1.531,the viscosity was 4720 mpa.s,and the refractive index was 1.526.(2)Under the catalysis of basic anion exchange resin,a series of high refractive index epoxy-modified vinyl methyl phenyl silicone resins with different content of vinyl groups(EVMPS)was prepared by non-hydrolytic sol-gel reaction between HMPS synthesized in the(1),vinyltrimethoxysilane(VTMS)and 3-glycidyloxypropylmethyldimethoxysilane(GPMDMS).and its synthesis process was optimized and characterized.Under the optimal synthesis conditions,the molecular weight of EVMPS was 3796,the molecular weight distribution index was 1.514,the viscosity was 4327 mPa.s and the refractive index was 1.534.(3)Under the catalysis of basic anion exchange resin,amine phenyl silicone resin(APS)with high refractive index was prepared by non-hydroltic sol-gel reaction between diphenylsilanediol(DPSD)and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane(AEAPTMS).And the synthesis process of APS was optimized and the performance also was characterized.Under the optimal synthesis conditions,the molecular weight of APS was 598,the molecular weight distribution index was 1.336,the viscosity was 349 mpa.s and the refractive index was 1.519.(4)Epoxy modified silicone materials(AEMPS)were obained by addition reaction between epoxy modified silicone resins(EMPS)and amine phenyl silicone resin(APS).And curing reaction between epoxy modified silicone resins and amine phenyl silicone curing agent can be completed at 80°C for 2h,and their properties were characterized.The results showed that AEMPS had high transmittance(> 90%)in the wavelength range of 450~800nm,indicating good compatibility between EMPS and APS.And AEMPS had good mechanical properties(80 shoreA)and thermal stability.Red ink experiments showed that AEMPS has good adhesion to LED substrate.Epoxy-modified vinyl silicone materials(EVMPS’)were manufactured by addition reaction between epoxy-modified vinyl methyl phenyl silicone resins(EVMPS)and hydrogen-containing phenyl silicone resin(HPS)under the condition of 90°C for 1h and 150°C for 2h,and their performance was characterized.The results showed that EVMPS’ had high light transmittance(>90%)and good thermal stability.Compared with commercial epoxy resin(6103),EVMPS’ had excellent resistance to high temperature and ultraviolet resistance.And the introduction of epoxy groups greatly improved the adhesion of silicone resin to LED substrate.(5)Through a great many of exploration experiments,the mechanism of opening-ring of epoxy groups causing the product gel in the sol-gel reaction was analyzed.And the synthetic process of epoxy modified silicone resin was optimized,which provides a theoretical basis for stablity of epoxy groups during the reaction and preparation of epoxy modified silicone resin.